一个新的激活策略在偏κ—树上的应用

笔者使用一个新的激活策略证明了 ,如果G是一个偏k -树 ,其色数为r=k + 1 ,缺陷度d≥ 2k + 1 ,那么 ,对这个 (r,d) -松弛竞赛染色 ,Alice有一个赢的策略。这个结果可以写为 ( 2k+ 1 ) - χg(G)≤k+ 1 ,它是文献 [3]中相应结果的一个改进     

改进的快速扩展随机树在航迹规划中的应用

通过在快速扩展随机树(rapidly-exploring random tree)算法的基础上融入状态-时间空间(state-timespace)的思想,使改进后的算法能够有效地处理动态环境中的航迹规划问题。仿真试验首先采用四元素法建立航天飞行器的六自由度动力学模型,在三维空间中验证该算法搜索高维空间的能力。其次运用改进的算法在动态环境中进行航迹规划试验,证明了该算法的有效性。     

新疆石河子-沙湾地区博尔通古牧场硬蜱形态学和16S rDNA序列分析研究

为了掌握新疆石河子-沙湾地区博尔通古牧场畜牧体表寄生硬蜱的分布情况及物种多样性,对该地区12个调查点的寄生蜱类进行考察,采用形态学分类及16S rDNA序列进行遗传进化分析的方法对采集的323只羊和228只牛寄生硬蜱进行研究,从中选取26只硬蜱进行线粒体16S rDNA序列扩增、测序,并与34种GenBank参考序列进行遗传进化分析。结果显示:该地区共鉴定出2科3属7个种的硬蜱。其中2种硬蜱与边缘革蜱(Z97879)16S rDNA序列同源性分别为98.2%和96.8%,遗传距离为0.021和0.026;1种硬蜱与森林革蜱(JF979379)、草原革蜱(JF979375)16S rDNA序列的同源性为95%和96.3%,遗传距离为0.039和0.042;3种硬蜱基因序列与亚洲璃眼蜱(JF979380)16S rDNA的同源性为98.3%~99.8%,遗传距离为0.003~0.017;且获得的1种硬蜱,与刻点血蜱(Z97880)同源性完全相同。结论:首次应用形态学和16S rDNA序列分析报道了新疆石河子-沙湾地区博尔通古牧场牛、羊体表寄生的硬蜱种类,16S rDNA测序分析表明该地区硬蜱与GenBank报道的国际硬蜱有一定差异性,与国内其它省份分离的硬蜱16S rDNA序列亦不完全相同,具有区域差异性。     

一种基于随机生成树的多维Q选择算法

射频识别（ Radio Frequency Identification,RFID）中,当标签密度较大时,系统工作效率常常因标签发生碰撞而降低,甚至导致通信错误,这时需要应用防碰撞算法进行纠正。本文在ISO/IEC 18000-6 Type C标准所采用的Q选择防碰撞算法基础上,提出了基于随机生成树的多维Q选择算法（ Multiple Dimensional Q-Selection with Random Tree,MDQRT）。该算法实现了随机Q选择算法与确定性算法的结合。仿真结果显示,该方法降低了设备及能量损耗,并有效提高了整个系统的识别效率。     

基于SIFT的软骨切片电镜图像拼接算法

软骨组织断层的电镜图像拼接是人工软骨组织培养过程中的关键技术之一.对二维断层电镜图像的拼接方法进行了深入研究,利用SIFT算法对图片进行关键点检测,利用kd-tree建立数据索引,进行关键点的快速匹配,确定图像位移,实现了局部断层图像的无缝拼接,有效解决了电镜图像视角小的问题.在VS2010环境下利用C语言进行仿真,实验表明,该方法具有鲁棒性强、实时性好的特点.证明该方法可以为人工软骨组织的培养提供客观的科学支持.     

5-桥图的色性

由连接两个顶点的s条内部不交的路组成的图叫s-桥图,记作F（k1,k2,…,ks）.本文给出了5-桥图F（3,a,b,c,d）（d≥c≥b≥a≥3）是色唯一的充分必要条件.     

无线传感器网络低时延能量均衡安全路由

提出了一种能量均衡的安全路由机制(LDEESR),适用于周期性数据收集的传感器网络.LDEESR 采用一种动态路由选择算法,该算法基于节点权值和高度值建立起一棵动态汇聚树,并利用类似于令牌传递的方式来选取树根,同时还用对称和非对称加密机制来保障路由的安全.在这种机制下,LDEESR 能够以很低的开销组织网络中所有的节点,健壮网络拓扑,防范多种攻击.通过与基于群体的传感网络以及混合式高能效分布式聚类协议的仿真比较表明,LDEESR 可降低和均衡所有节点的能耗,减小汇聚时延,延长网络的生命期.     

Magnetic response to atmospheric heavy metal pollution recorded by dust-loaded leaves in Shougang industrial area,western Beijing

Fifty-five evergreen tree＇s leaves growing less than one year were collected from Shougang industrial area in western suburb of Beijing, including steel plants and its ambient residential areas, recreational parks and farmlands. Rock magnetic properties and heavy metal contents were studied. The results show that the magnetic properties of leaf samples are predominated by Iow-coercivity magnetite, and both the concentration and grain size of magnetite particles gradually decreased with the distance from the main pollution source increases. Moreover, there is a significant linear relationship between magnetic parameters （the low-field magnetic susceptibility, saturation isothermal remanent magnetization and anhysteretic remanent magnetization） and heavy metals contents （Fe, Pb, V, Cr and Zn） （0.73≤ R≤ 0.88）. Hence, the magnetic parameters of leaves can serve as a proxy for quick detecting of the recent atmospheric metallic pollution.     

Millennial temperature reconstruction based on tree-ring widths of Qilian juniper from Wulan, Qinghai Province, China

The climate of the past 1000 years is an important context for evaluating the recent climate warming. However, there are few 1000-year-long climate reconstructions with annual resolution in the Qinghal-Tibet Plateau. In this paper, a dendroclimatic analysis was conducted for the radial growth of Qilian juniper from the upper forest limit in Wulan, Qinghai Province. The results of correlation analysis between the tree-ring widths and the climate variables indicate that the growth of junipers at the upper forest limit is mainly limited by low temperatures of September, November and February of the pregrowth season, and July of the current growth season. There is no significant correlation between the tree-ring widths and precipitation. A mean temperature from the previous year＇s September to the current year＇s April was reconstructed for the Wulan area since A.D. 1000. The reconstruction can explain 40.8% of the instrumental variance in the calibration period （1856-2002）. The reconstruction shows that the 20th century is the warmest 100 years, and the 1990s is the warmest decade during the past 1000 years, while the coldest 100 years and decade occur at 1600-1699 and 1642-1651, respectively. The variations are verified well by the temperature reconstruction of the middle Qilian Mountain （QL） and the total organic carbon （TOC） in the Qinghai Lake sediments. The comparison of our reconstruction with the annual temperature reconstruction of extra-tropical Northern Hemisphere suggests that the climate of Wulan during the Medieval Warm Period is of obvious regional specialty, but there was a good response to the climate of hemispheric scales during the recent 400 years.     

基于用户操作树的内部威胁检测模型

企业组织网络所面临的威胁不仅来自外部,而且也来自内部,而内部威胁(Insider Threat)已被认为是一个非常严重的安全问题.现在,内部威胁分析检测工具方面的研究仍处于探索阶段,笔者提出一种新颖的基于用户操作树的内部威胁检测模型.该模型依据用户对系统的操作,定制生成该用户的操作树,通过分析用户操作树可以预测内部威胁的存在.